Cathers are currently used for a variety of medical purposes in a wide range of both diagnostic and therapeutic applications. Catheters are, by way of example, most commonly used in the peripheral blood vessels (i.e. those close to the skin) to support and maintain blood volume levels, to introduce medications into the blood stream, and to provide nutritional support. Catheters are also used in arterial vessels to monitor certain blood parameters and to deliver regional chemotherapy. Connections to veins deep within the body may be established to obtain localized blood samples, to deliver nutritional compounds, to measure cardiac output and, in some cases, may be implanted on a semi-permanent basis to deliver chemotherapeutic compounds or to maintain a continuous mode of central venous access. Catheters are also commonly used in the urinary tract.
While the foregoing listing is far from exclusive, each of these utilities is associated with a substantial risk of infection or clotting in and around the catheter, particularly where the catheter remains in situ for an extended period of time. While the exact causes of all such complications are not completely known, conventional efforts to reduce or eliminate intravascular device-associated infection presently take several forms. The first usually involves pre-insertion cleansing of the skin surface surrounding the area of penetration to prevent contamination of the device as it penetrates the skin by infectious agents which are present on the skin surface. Regular removal and replacement of the intravascular device every two to three days, for example, is also a common anti-infective procedure. Furthermore, different materials such as Telfon (PTFE) and polyvinylchloride (PVC) have been used in the manufacture of catheters, each having demonstrated some ability to prevent the onset of infection by discouraging infectious agents from adhering to and growing on the catheter surface. More recently, catheters have also become available with anti-microbial agents bonded to the exterior surface of the catheter. None of these currently known devices or procedures, however, has proven to be sufficiently effective successful in preventing the onset of infection or clotting within the catheter, or on or along the exterior portions of the catheter that extend into the body.